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European stocks sold off Friday, wrapping up their worst week in nine months, as the war of words between the U.S. and North Korea prompted investors to back away from assets perceived as risky.

The Stoxx Europe 600 closed down 1% to 372.14, the weakest finish since Feb. 28. No sector finished higher.

For the week, the index fell 2.7%, the worst week since early November 2016 (http://www.marketwatch.com/story/european-stocks-face-worst-week-in-9-months-rattled-by-political-risk-2016-11-04), just before the U.S. presidential election was held.

"The weekend brings an undefined amount of risk for investors, with the potential for circumstances to escalate both dramatically and unexpectedly at a time when markets are closed," wrote Oanda's senior market analyst Craig Erlam.

"In the unlikely event that either side follows through on the threats of recent days and an attack occurs, we could see some dramatic moves at the open next week, something investors in perceived riskier assets would be very vulnerable to," he added.

Read:Dalio urges investors to buy gold to hedge against possible war with North Korea (http://www.marketwatch.com/story/dalio-urges-investors-to-buy-gold-to-hedge-against-possible-war-with-north-korea-2017-08-10)

European equities extended losses Friday after U.S. President Donald Trump on Thursday warned that his threat on Tuesday to unleash "fire and fury" on North Korea "maybe wasn't tough enough." Trump's comments came as North Korean leader Kim Jong Un made an explicit threat to strike a U.S. military base in Guam (http://www.marketwatch.com/story/north-korea-threatens-missile-strike-on-us-base-on-guam-2017-08-08).

China weighed in on the standoff late Thursday, saying in an editorial in state-run Global Times (http://www.globaltimes.cn/content/1060791.shtml) that Beijing will intervene if the U.S. strikes first against North Korea.

Read:Opinion: What to do with stocks if the U.S. and North Korea go to war (http://www.marketwatch.com/story/what-to-do-with-stocks-if-the-us-and-north-korea-go-to-war-2017-08-10)

The International Energy Agency said in its monthly report (http://www.marketwatch.com/story/oil-supply-rises-as-opec-deal-compliance-falters-2017-08-11) that global oil production rose in July, but it also upwardly revised its 2017 forecast for demand growth.

In other developments, Novozymes A/S shares (NZYM-B.KO) flipped higher to close up 1.2%. The shares had dropped during the session after the Danish biotech firm cut its growth outlook.

National indexes: France's CAC 40 index fell 1.1% to 5,060.92, and in London, the FTSE 100 flopped down 1.1% (http://www.marketwatch.com/story/ftse-100-heads-for-1-month-low-as-trump-ups-the-ante-in-north-korea-standoff-2017-08-11) to 7,309.96. Spain's IBEX 35 gave up 1.6% to close at 10,282.90.

But Germany's DAX 30 ended down less than 1 point at 12,014.06. The index during the session fell below 12,000 as well as its 200-day moving average.

The euro (http://www.marketwatch.com/story/dollar-trades-in-narrow-range-ahead-of-key-inflation-data-2017-08-11) bought $1.1822, up from $1.774 late Thursday in New York.

Read:These are the stocks to buy--and avoid--as the euro rallies (http://www.marketwatch.com/story/these-are-the-stocks-to-buyand-avoidas-the-euro-rallies-2017-08-11)